Infectious mononucleosis is characterised by the classic triad of fever, pharyngitis, and lymphadenopathy, along with atypical lymphocytosis. It is often subclinical in young children.
Caused by infection with Epstein-Barr virus (EBV) in 80% to 90% of cases. Positive heterophile antibody test and serological test for antibodies against EBV are usually diagnostic.
Rare but potentially life-threatening complications include severe upper airway obstruction, splenic rupture, fulminant hepatitis, encephalitis, severe thrombocytopaenia, and haemolytic anaemia.
Treatment is usually symptomatic.
Infectious mononucleosis (IM), also known as glandular fever, is a clinical syndrome most commonly caused by Epstein-Barr virus (EBV) infection in 80% to 90% of cases. Other causes are much less common. The diagnosis 'infectious mononucleosis' is primarily used when the syndrome is caused by EBV; 'mononucleosis syndrome' should be used when the syndrome is caused by a non-EBV aetiology. This topic focuses on IM caused by EBV.
IM typically manifests in adolescents and young adults as a febrile illness with sore throat and enlarged lymph nodes. Atypical lymphocytosis and a positive heterophile antibodies test are usually observed. The disease is generally mild in children, but more severe in adults. Resolution of the acute illness is usually followed by a lifelong latent infection, with over 90% of the adult population infected worldwide.
History and exam
Key diagnostic factors
- presence of risk factors
- cervical or generalised lymphadenopathy
Other diagnostic factors
- signs of hepatitis (hepatomegaly, jaundice)
- sexual behaviour
1st investigations to order
- heterophile antibodies
- Epstein-Barr virus (EBV)-specific antibodies
Investigations to consider
- real-time polymerase chain reaction (PCR)
- ultrasonography of abdomen
- CT of abdomen
- Group A streptococcal pharyngitis
- Hepatitis A
- Acute HIV infection
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